Dinuclear copper(I) benzoato complexes binding isocyanides and azo

compound, produces two different complexes depending on the reaction solvent. ... The reaction of 1 with azo compounds led to polymeric structures whe...
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Inorg. Chem. 1987, 26, 236-241

236

Contribution from the Dipartimento di Chimica e Chimica Industriale, Universitg di Pisa, 56100 Pisa, Italy, Chemistry Department, Columbia University, New York, New York 10027, and Istituto di Strutturistica Chimica, Centro di Studio per la Strutturistica Diffrattometrica del C N R , Universitl di Parma, 43100 Parma, Italy

Dinuclear Copper(I) Benzoato Complexes Binding Isocyanides and Azo Compounds Andras Toth,+ Carlo Floriani,*t Angiola Chiesi-Villa,g and Carlo Guastinis Received June IO. 1986 The copper(1)-benzoato complex [Cu(PhCO,)], (1) is a source of the doubly bridged dimetallic unit [Cu,(p-PhCO,),] in reaction with many substrates. Reaction with isocyanides, which parallels the reaction with carbon monoxide, leading to a very labile compound, produces two different complexes depending on the reaction solvent. In ethanol the dimeric complex [Cu,(pPhC02)2(P-MeC6H4NC)2](4) [v(CN) (Nujol) = 2152 cm-'1, having the two copper(1) centers very close at 2.750 (2) A,formed. A significant intermolecular interaction involving the copper(1) of one dimer and the carbon of the isocyanide ligand of another dimer establishes a tetrameric structure in the solid state [Cu--Cu = 2.860 (2) A]. This intermolecular interaction does not occur in [CU~(~-P~CO,)~@-M~C~H~NC),I.THF (5), which formed when the reaction between 1 and p-MeC6H,NC was carried out in T H F [Cu-Cu = 3.020 (3) A;v(CN) (Nujol) = 2145 and 2125 cm-I]. In both complexes 4 and 5 the isocyanide has a terminal and semibridging bonding mode. The reaction of 1 with azo compounds led to polymeric structures where the [Cu,(p-PhCO,),] dimers are bridged by the azo functionality, from the lone pairs at the nitrogen atoms. The steric hindrance of the azo compound seems to play the major role in determining the Cu:azo ratio and the structure of the complex. Benzo[c]cinnoline reacted with 1 to form [Cu2(p-PhC02)2(p-benzo[c]cinnoline)],(6), containing the almost planar eight-membered ring [Cu,(p-PhCO,),]. The Cu-Cu distances are in turn 2.788 (2) and 3.262 (2) A along the polymeric chain. Phthalazine reacted with 1 to form [Cu2(p-PhC02)2(p-phthalazine)2],,(7)for which a polymeric structure analogous to that of 6 is proposed. The structures of complexes 4-6 have been determined. Complex 4: space group Pi (triclinic); a = 13.278 (4) A;b = 10.690 (3) A;c = 10.412 (2) A;CY = 104.20 (2)'; /3 = 95.71 (3)'; y = 104.75 (3)"; V = 1364.7 (7) A'; Z = 2; Dcald= 1.47 g cm3. The final R factor was 0.044 (R, = 0.046) for 2557 observed reflections. Complex 5: space group Pi (triclinic); a = 10.440 (2) A;b = 19.408 (4) A;c = 10.476 (2) A; a = 96.77 (2)'; /3 = 106.20 (2)'; y = 77.66 (2)'; V = 1987.4 (8) A'; Z = 2; D,,, = 1.32 g The final R factor was 0.048 for 3236 observed reflections. Complex 6: space group Pbcn (orthorhombic); a = 21.679 (3) A;b = 9.408 (1) A; c = 10.564 (2) A; V = 21 54.6 (5) A'; Z = 4; Da,d = 1.69 g ~ m - ~The . final R factor was 0.064 (R,= 0.064) for 1402 observed reflections.

Introduction There is currently a great attention paid to dinuclear copper(1) complexes.' Such species are extremely interesting since they c a n provide a two-site binding to small molecules and organic functionalities, and copper(1) has some special peculiarities. T h e major effort in this field is t o design appropriate binucleating ligands t h a t take care of having the two sites a t t h e appropriate distance.' A much simpler approach, which can be adopted in organometallic chemistry, is to use a source of dicopper(1) unit t h a t can survive in t h e presence of various ligands. Copper(1) carboxylates, which are tetrameric2or polymeric3 in the solid state, react with u and K ligands while maintaining the dimetallic unit."-' A further interest in copper(1) carboxylates derives from their ability t o promote catalytic hydrogenation via t h e heterolytic splitting of molecular hydrogen.* Therefore, t h e reaction of copper(1) carboxylates with unsaturated substrates that potentially can undergo hydrogenation seems particularly attractive. This reaction has been relatively poorly studied, except for few example~.~,' T h e present report concerns the reactivity of copper(I) benzoate with isocyanides and azo compounds, both reactions leading to complexes containing a dicopper(1) unit doublly bridged by t h e benzoato group. Terminal a n d semibridging isocyanide a n d bridging azo complexes have been isolated and structurally characterized.

Experimental Section Owing to the air sensitivity of the complexes, all reactions were carried out in a dry, oxygen-free atmosphere, with the use of standard Schlenk techniques. Solvents were purified by standard methods. Benzo[c]cinnoline (bzocin) and phthalazine (phz) were recrystallized before use. A modified procedure was used for the preparation of [Cu(PhCO,)],.' Cur9 and p-tolyl isocyanide1° were prepared by published procedures. Infrared spectra were recorded with a Perkin-Elmer 283 spectrophotometer. Synthesis of CU,(~-P~C~~)~[(P-M~C~H~NC),] (4). To a ethanol suspension of [Cu(PhCO,)], (0.347 g, 0.47 mmol) was added pMeC6H4NC(0.7 mL, 5.74 mmol). A white-yellow microcrystalline solid immediately formed, which was filtered and dried. The mother liquor

Universiti di Pisa. *Columbia University Universiti di Parma.

0020-1669/87/1326-0236$01.50/0

was partially evaporated, the solid formed was dissolved by gentle heating, and by subsequent slow cooling yellow crystals appropriate for X-ray analysis were obtained (yield ca. 20%). The two solids were identical by superimposable IR spectra. Anal. Calcd for Cg0H2,Cu2N 2 0 4 (4): C, 59.70; H, 4.01; N, 4.64. Found: C, 59.50; H, 4.47; N, 4.96. v(CN) (Nujol) = 2152 cm-l (s). A single C N band was observed in solution (EtOH) at 2152 cm-I. Synthesis of [CU~(~-P~CO~)~@-M~C~H~NC),]-THF (5). When a T H F suspension (20 mL) of [Cu(PhCO,)], (0.39 g, 0.53 mmol) was reacted with neat p-tolyl isocyanide (0.52 mL, 4.26 mmol), a yellow solution formed. After partial evaporation of the solvent a white solid formed, which was filtered and dried in vacuo (yield ca. 22%). A partial evaporation of the mother liquor gave the same solid, which was dissolved by gentle heating and crystallized by slow cooling. Colorless flat hexagonal crystals suitable for X-ray analysis were obtained. The two solids Karlin, K. D.; Cruse, R. W.; Gultneh, Y.; Hayes, J. C.; McKown, J. W.; Zubieta, J. In Biological and Inorganic Copper Chemistry; Karlin, K. D., Zubieta, J., Eds.; Adenine: Guilderland, NY, 1986; pp 101-114. Sorrell, T. N. Ibid., pp 41-55. Drew, M. G. B.; Yates, P. C.; TrochaGrimshaw, J.; McKillop, K. P.; Nelson, S. M. J . Chem. SOC.,Chem. Commun. 1985, 262-263. Karlin, K. D.; Hayes, J. C.; Gultneh, Y . ; Cruse, R. W.; McKown, J. W.; Hutchinson, J. P.; Zubieta, J. J . Am. Chem. SOC.1984, 106, 2121-2128. Sorrell, T. N.; Borovik, A. S. J . Chem. SOC.,Chem. Commun. 1984, 1489-1490. Castellani, C. B.; Millini, R. J. Chem. SOC.,Dalton Trans. 1984, 1461-1462. Rasmussen, P. G.; Anderson, J. E.; Bayon, J. C. Inorg. Chim. Acta 1984, 87, 159-164. Macomber, D. W.; Rausch, M. D. J . Am. Chem. SOC.1983, 105, 5325-5329. Villacorta, G. M.; Gibson, D.; Williams, I. D.; Lippard, S. J. Ibid. 1985, 107, 6732-6734. Drew, M. G. B.; Edwards, D. A.; Richards, R. J. J. Chem. Soc., Dalton Trans. 1977, 299-303. Drew, M. G. B.; Edwards, D. A.; Richards, R. J . Chem. SOC.,Chem. Commun. 1973, 124-125. Edwards, D. A.; Richards, R. J . Chem. Soc., Dalton Trans. 1973, 2463-2468. Edwards, D. A.; Richards, R. J . Chem. Soc., Dalton Trans. 1975, 637-643. Hammond, B.; Jardine, F. H.; Vohra, A. G. J . Inorg. Nucl. Chem. 1971, 33, 1017-1024. Edwards, D. A.; Richard, R. J. Organomet. Chem. 1975,86,407-414. Reger, D. L.; Dukes, M. D. Ibid. 1976, 113, 173-185. Pasquali, M.; Leoni, P.; Floriani, C.; Gaetani-Manfredotti, A. Inorg. Chem. 1982, 21, 4324-4328. Pasquali, M.; Floriani, C.; Venturi, G.; Gaetani-Manfredotti, A,; Chiesi-Villa, A. J. Am. Chem. Soc. 1982, 104, 4092-4099. Doyle, G.; Eriksen, K. A,; Modrick, M.; Ansell, G. Organometallics 1982, 1 , 1613-1 618. James, B. R. In Homogeneous Hydrogenation; Wiley: New York, 1973; Chapter 11. Brauer, G. Handbook of Preparative Inorganic Chemistry, 2nd ed.; Academic: New York, 1965; Vol. 2; pp 1005-1007. Appel, V. R.; Kleinstuck, R.; Ziehn, K. D. Angew. Chem. 1971,83, 143.

0 1987 American Chemical Society

Dinuclear Copper( I) Benzoato Complexes

Inorganic Chemistry, Vol. 26, No. 2, 1987 237

Table I. Crystal Data and Summary of Intensity Data Collection and Structure Refinement complex 4 complex 5 C30H24CU2N204

cryst syst space group cell dimens at 295 K

C26H18CU2N204

triclinic

triclinic

Pi [Cf, No. 21

Pi [Cf, No. 21

orthorhombic Pbcn [D& No. 601

13.278 (4) 10.690 (3) 10.412 (2) 104.20 (2) 95.71 (3) 104.75 (3) 1364.7 (7)

10.440 (2) 19.408 (4) 10.476 (2) 96.77 (2) 106.20 (2) 77.66 (2) 1987.4 (8) 2 1.32 792.9 0.11 X 0.29 X 0.42 16.50

21.679 (3) 9.408 (1) 10.564 (2) 90 90 90 2154.6 (5) 4 1.69 549.5 0.40 X 0.19 X 0.74 20.16

el20 3-12 (0 - 0.5')-[0 + (0.5 + Ab')]" Ni-filtered Cu Ka (A = 1.5418 A)

Nb-filtered Mo K a (A = 0.7107

*h,fk,+l

ih,*k,+l

+h,+k,+l

6-48 4232 2557 I>344 295 0.044 0.046 1.22 8.7 1.52-1.26

6-1 10 4943 3236 I>2 4 0 404 0.048

6-52 2134 1402 I>240 154 0.064 0.064 0.28 9.0 1.88-1.37

a, A

b, A

c, A a,deg

6, deg Z

L

g mol wt max cryst dimens, mm linear abs, cm-I diffractometer scan type scan speed, deg m i d scan width radiation reflecns measd 20 range, deg unique total data unique obsd data (No) criterion for observn no. of params varied (N,) R20 Rw20

1.47 603.6 0.18 X 0.32 X 0.61 15.98 Siemens AED

&ld,

GOF~I

No:Nv Ab a A0

= (Aa2

- A,,)/A

complex 6

C42H39CU2N305

A)

Nb-filtered Mo K a (A = 0.7107

tan 0.

8.0

1.48-1 .I6

A)

Maximum-minimum transmission factors.

Table 11. Fractional Atomic Coordinates ( X 10 000) for Complex 4 atom c u1 cu2 01A 02A NlA 01B 02B NIB CIA C2A C3A C4A C5A C6A C7A C8A C9A ClOA C11A

xla 3192 (1) 1080 (1) 2977 (4) 1291 (4) 3510 (4) 3403 (4) 1695 (4) 485 (4) 3393 (5) 3662 (3) 3706 (3) 3869 (3) 3989 (3) 3945 (3) 3782 (3) 4223 (7) 2167 (5) 2261 (3) 1447 (3)

ylb 1968 (1) 566 (1) 1920 (4) 674 (5) 4416 (5) 183 (4) -986 (5) 2128 (5) 3455 (7) 5584 (3) 6797 (3) 7975 (3) 7940 (3) 6727 (3) 5549 (3) 9224 (7) 1238 (6) 1071 (4) 158 (4)

ZIC

635 -91 -1305 -1916 2925 484 -68 2355 2049 3944 3645 4682 6018 6317 5280 7142 -2164 -3622 -4622

(1) (1) (4) (4) (5) (4) (5) (5) ( 6) (3) (3) ( 3) (3) (3) (3) (7) (6) (3) (3)

were identical. Anal. Calcd for C42H39C~2N305 (5): C, 63.63; H, 4.96; N , 5.30. Found: C, 63.62; H, 4.79; N, 5.44. Complex 5 has two C N bands (Nujol) at 2125 (m-s) and 2145 cm-I (s). In T H F solution a wide intense band was observed at 2140 cm-I. Synthesis of [C~~(p-PhCO~)~(p-bzocin)~ (6). Benzo[c]cinnoline (1 .O g, 5.55 mmol) was dissolved in T H F (25 mL), and then [Cu(PhC02)], was added with vigorous stirring. Sudden formation of a brown microcrystalline solid occurred (yield ca. 80%). The recrystallization of 6 was carried out as follows: When a suspension of 6 in T H F was exposed to carbon monoxide [v(CO) = 2075 cm-'1, the compound became slightly more soluble. The suspension was filtered under CO, and then the CO atmosphere was slowly removed from the resulting solution. Black hexagonal crystals suitable for X-ray study were obtained. The crystallization did not change the nature of the solid. Anal. Calcd for C 2 6 H 1 8 C ~ 2 N 2(6): 0 4 C, 56.83; H, 3.30; N , 5.10. Found: C, 57.03; H, 3.30; N, 5.12. Synthesis of [Cu(p-PhC02)(p-phz)L (7). To a T H F solution (30 mL) of phthalazine (0.73 g, 5.61 mmol) was added [Cu(PhC02)], (1.04 g, 1.405 mmol) as a solid. The solid dissolved, giving a red solution.

atom C12A C13A C14A C15A ClB C2B C3B C4B C5B C6B C7B C8B C9B ClOB CllB C12B C13B C14B C15B

xla 1551 (3) 2471 (3) 3285 (3) 3180 (3) 693 (5) 221 (3) 934 (3) 646 (3) -355 (3) -1067 (3) -779 (3) -700 (7) 2659 (5) 2947 (3) 2156 (3) 2427 (3) 3488 (3) 4278 (3) 4008 (3)

ylb -50 (4) 656 (4) 1569 (4) 1777 (4) 1542 (6) 2693 (4) 2995 (4) 3482 (4) 3665 (4) 3362 (4) 2876 (4) 4135 (9) -902 (7) -2192 (3) -3415 (3) -4615 (3) -4592 (3) -3369 (3) -2169 (3)

ZIC

-5972 (3) -6322 (3) -5322 (3) -3972 (3) 1374 (6) 3573 (3) 4762 (3) 5999 (3) 6048 (3) 4859 (3) 3622 (3) 7401 (7) 156 (6) 35 (4) -258 (4) -408 (4) -266 (4) 28 (4) 178 (4)

Evaporation of ca. one-third of the solvent resulted in the formation of a crystalline solid (yield ca. 71%). Anal. Calcd for CI5HiiCuN2O2(7): C, 57.23; H, 3.52; N, 8.89. Found: C, 56.81; H, 3.52; N, 8.73. Synthesis of [Cu212(bzocin)](8). CUI (0.50 g, 2.62 mmol) was added to a T H F solution (20 mL) of benzo[c]cinnoline (0.52 g, 2.88 mmol). Sudden formation of a dark brown precipitate was observed. The suspension was stirred overnight. The dark brown solid was filtered; from the yellow solution no crystalline material was recovered. Anal. Calcd for CI2H8Cu2I2N2 ( 8 ) : C, 25.69; H , 1.44; N, 4.99. Found: C, 25.72; H, 1.41; N , 4.97. Synthesis of [CuI(phz)], (9). CUI (1.0 g, 5.25 mmol) was added to a T H F solution (20 mL) of phthalazine (0.70 g, 5.38 mmol). Sudden formation of a largely insoluble orange solid was observed (yield ca. 60%). Attempts to recover crystalline material from the solution and recrystallization of the solid were unsuccessful. Anal. Calcd for C8H6CuIn2(9): C, 29.97; H, 1.89; N, 8.73. Found: C , 30.52; H, 2.06; N, 8.33. X-ray Crystallography. The crystals selected for study were mounted in glass capillaries sealed under nitrogen. Extensive preliminary inves-

Toth et al.

238 Inorganic Chemistry, Vol. 26, No. 2, 1987 Table 111. Fractional atom c u1 cu2 NIA CIA C2A C3A C4A C5A C6A C7A C8A 01A 02A C9A ClOA CllA C12A C13A C14A C15A NIB ClB C2B C3B C4B C5B C6B C7B C8B

Atomic Coordinates (XlOOOO) for Complex 5" xla 2320 (1) 2566 (1) 4744 (6) 3783 (8) 5846 (5) 7090 (5) 8172 (5) 8010 (5) 6766 (5) 5684 (5) 9187 (9) 2383 (5) 2345 (4) 2286 (6) 2074 (4) 1997 (4) 1714 (4) 1509 (4) 1586 (4) 1869 (4) 4689 (5) 3887 (6) 5676 (4) 6935 (4) 7921 (4) 7647 (4) 6387 (4) 5402 (4) 8708 (7)

Ylb 2002 (1) 3462 (1) 2007 (3) 2054 (4) 2062 (3) 2118 (3) 2215 (3) 2257 (3) 2202 (3) 2104 (3) 2382 (6) 2517 (3) 3604 (2) 3168 (4) 3471 (2) 3022 (2) 3303 (2) 4032 (2) 4481 (2) 4200 (2) 3862 (3) 3704 (4) 4043 (2) 4115 (2) 4299 (2) 4411 (2) 4339 (2) 4155 (2) 4628 (4)

ZIC

427 (1) 1710 ( I j 2786 (6) 1904 (7) 3878 (4) 3688 (4) 4784 (4) 6070 (4) 6260 (4) 5164 (4) 7249 (9) -1 160 (4) -192 (4) -1175 (6) -2504 (3) -3655 (3) -4891 (3) -4977 (3) -3826 (3) -2590 (3) 4072 (5) 3152 (6) 5203 (3) 5076 (3) 6196 (3) 7441 (3) 7567 (3) 6448 (3) 8655 (6)

atom 01B 02B C9B ClOB CllB C12B C13B C14B C15B NlC ClC c2c c3c c4c c5c C6C c7c C8C c1 c2 c3 c4 c5 C1' C2' C3' c4 C5'

xla 376 (4) 663 (4) -46 (6) -1551 (3) -2057 (3) -3452 (3) -4341 (3) -3835 (3) -2440 (3) 1333 (7) 1813 (8) 647 (5) 798 (5) 66 (5) -816 (5) -968 (5) -236 (5) -1624 (5) 4272 (24) 3694 (38) 4296 (70) 6071 (57) 6181 (52) 5527 (74) 5000 (68) 5296 (72) 4778 (52) 5171 (67)

Ylb 2424 (3) 3462 (2) 3020 (4) 3236 (3) 3907 (3) 4129 (3) 3680 (3) 3009 (3) 2787 (3) 676 (3) 1141 (4) 156 (2) -484 (2) -996 (2) -868 (2) -228 (2) 284 (2) -1415 (2) 1127 (12) 576 (22) -28 (34) 85 (29) 857 (28) 617 (51) 9 (33) -19 (33) 781 (29) 1043 (31)

ZIC

626 (5) 1703 (4) 11 14 (6) 992 (4) 1490 (4) 1325 (4) 662 (4) 164 (4) 329 (4) -1074 (6) -490 (7) -1796 (5) -1237 (5) -1934 (5) -3190 (5) -3749 (5) -3052 (5) -3917 (5) 7472 (25) 6799 (35) 7168 (80) 7854 (62) 8223 (46) 9041 (70) 8295 (70) 6826 (60) 6555 (47) 8534 (71)

"Cl-C5 and CI*-C5* are the atoms of the disordered T H F molecule. Table IV. Fractional Atomic Coordinates (XlOOOO) for Complex 6 atom cu 01 02 N1 c1 c2 c3 c4 c5

xla 145 (1) 876 (2) 627 (2) 181 (2) 1598 (2) 1993 (3) 2559 (3) 2739 (3) 2363 (3)

ylb 928 (1) 984 (4) -282 (4) 3124 (4) 861 (5) 1792 (6) 2133 (7) 1551 (8) 618 (8)

z lc 985 0 -1686 2006 -1651 -1026 -1529 -2662 -3290

(1) (3) (3) (4) (4) (5) (6) (6) (6)

tigations employing rotation and Weissenberg photographs showed the crystals of complex 6 to be orthorhombic with systematic absences consistent with the space group Pbcn. The lack of any systematic absences indicated the crystals of 4 and 5 to be triclinic. Crystal data and details of data collection are given in Table I. Three-dimensional intensity data were collected at room temperature (295 K) on a single-crystal diffractometer. For intensities and background the profile measurement technique was used." The structure amplitudes were obtained by means of standard Lorentz and polarization reduction, and the absolute scale was established by Wilson's method.12 No absorption corrections were applied. Solution and Refinement of the Structures." The structures were solved by the heavy-atom method starting from three-dimensional Patterson syntheses and refined by full-matrix least squares anisotropically for all non-hydrogen atoms. For the three complexes all hydrogen atoms were located from different Fourier syntheses and introduced as fixed atom contributions with isotropic temperature factors fixed at 9.5 A2 for complexes 4 and 5 and 6.3 A2 for complex 6. For complexes 4 and 5 the benzene rings were refined as rigid groups having D6,, symmetry (C-C = 1.39 A). The function minimized during the least-squares refinement was CwlAF12. The weighting scheme used was w = k/[$(F,) + ld(Fo)2] based on counting statistics; k was redetermined after each structure (1 1) Lehmann, M. S.; Larsen, F. K. Acta Crystallogr., Sect. A: Cryst. Phys., D'ffr., Theor. Gen. Crystallogr. 1974, A30, 580-584. (12) Wilson, A. J. C. Nature (London) 1942, 150, 151-152.

(13) Data reduction, structure solution, and refinement were carried out on the CYBER 7600 computer of the Centro di Calcolo Interuniversitario dell'Italia Nord-Orientale, using the SHELX-76 system of crystallographic computer programs (Sheldrick, G., University of Cambridge, 1976). Calculations were performed with the financial support of the University of Parma.

atom C6 c7 C8 c9 c10 c11 c12 C13

xla 1781 (3) 984 (2) 393 (2) 219 (2) 486 (3) 898 (3) 1056 (3) 804 (3)

ylb 286 (6) 494 (5) 4388 (5) 5728 (5) 6951 (6) 6836 (6) 5512 (7) 4292 (5)

zlc

-2794 (5) -1082 (5) 1517 (5) 2009 (6) 1476 (6) 497 (7) -16 (6) 493 (6)

factor calculation, and the absolute value of g was refined at the same time by fitting (IFol - lFc1)2to [$(Fo) ld(Fo)Z]/k.13In the final stage of refinement the values for k and g were 1.1015, 0.000616 and 0.4981, 0.01 16 for complexes 4 and 6, respectively. Unit weights were used for complex 5 since these gave a satisfactory analysis of variance." During the refinement of complex 5, the appearance in a difference density map of 10 peaks in a region far from the complex molecule indicated the presence of solvent of crystallization. This could be interpreted as one disordered T H F molecule distributed over two positions with a site occupancy factor of 0.5. Final isotropic temperature factors for these "partial" atoms ranged from 12 to 22 A*, indicating a high thermal motion associated with disorder in this group. The effects of the anomalous dispersion were included in all structure factor calculations.14b Scattering factors were taken from ref 14a and Cu, from ref 15 for 0, N , and C, and from Ref 16 for H .

+

Results and Discussion Reaction of [Cu(PhCO,)L with Isocyanides. Copper(1) benzoate, [Cu(PhC02)14, which has the well-known tetrameric structure,, is a very good source of the dinuclear copper(1) unit [ C U ~ ( P ~ C Oin~ )the ~ ] presence of various ligands like diphenylacetylene6 and carbon monoxide.' In the latter case, for which the isolation of carbonyl species in the solid state failed ( 14) International Tablesfor X-ray Crystallography;Kynoch: Birmingham,

England, 1974; Vol. IV: (a) p 99; (b) p 149. ( 1 5 ) Cromer, D. T.; Mann, J. B. Acta Crystallogr., Sect. A Cryst. Phys., Diffr., Theor. Gen. Crystallogr. 1968, A24, 321-324. (16) Stewart, R. F.; Davidson, E. R.; Simpson, W. T. J . Chem. Phys. 1965, 42, 3175-3187.

Dinuclear Copper(1) Benzoato Complexes

Inorganic Chemistry, Vol. 26, No. 2, 1987 239

Table V. Interatomic Distances (A) and Angles (deg) for Complexes 4 and 5‘ 4 CU1-01 A Cul-OlB Cul-Cl A c u 1-c 1c Cul-cu2

5

1.998 (4) 1.969 (5 j 1.823 (6)

2.061 2.078 1.857 1.926 3.020

2.750 (2)

OlA-C9A 02A-C9A N1 A-Cl A NlA-C2A C9A-C 10A N 1C-ClC C5A-C8A c5c-c 8C

1.256 (7) 1.250 (8) 1.159 (8) 1.380 (5) 1.506 (7)

93.5 (3) 100.0 (3) 102.0 (2) 125.3 (3) 118.4 (3) 113.5 (3) 172.3 (7) 178.2 (6) 170.8 (8) 171.2 (7) 179.0 (7) 175.0 (8) 125.2 (4) 128.2 (5) 130.3 (4) 127.2 (4)

100.2 (2)

C 1A-Cu 1-C 1C C 1A-CU 1-0 1 B C 1A-Cul-0 1A C U1-C 1A-N1 A Cu2-C 1 B-N 1B CU1-C 1C-N 1C ClA-NlA-C2A C 1B-N 1B-C2B ClC-NlC-C2C CUl-OlA-C9A C U1-01 B-C9B Cu2-02A-C9A Cu2-02B-C9B

133.3 (3) 125.4 (3) 178.2 (6) 175.6 (6) 178.3 (6) 173.4 (6) 125.9 (4) 123.8 (5) 122.5 (4) 126.0 (5)

5

4 1.975 (5) 2.031 (6) 1.824 (6) 2.757 (7)

Cu2-02A Cu2-02B Cu2-ClB Cu2-C 1B’ Cu2-C 1A cu2-Cu2’ OlB-C9B 02B-C9B N1 B-Cl B N1B-C2B C9B-C 1OB N 1C-C2C C5B-C8B

1.247 (10) 1.250 (8) 1.154 (9) 1.390 (7) 1.516 (8) 1.154 (10) 1.518 (9) 1.501 (6)

1.508 (7)

0 1B-Cul-Cl C 0 1A-Cu 1-C1 C 0 1A-Cu 1-01 B

(6) (5j (7) (8) (3)

1.986 (5) 1.985 (5) 1.831 (6) 2.762 (8)

2.860 (2) 1.262 (7) 1.254 (9) 1.159 (8) 1.384 (6) 1.502 (9)

1.250 (8) 1.248 (8) 1.146 (7) 1.402 (6) 1.510 (7) 1.389 (8) 1.520 (7)

1.531 (9)

02A-Cu2-C 1B 02A-Cu2-02B C1 B-Cu2-02B C 1A-Cu2-C 1B ClA-Cu2-02A ClA-Cu2-02B C 1Bt-Cu2-02A ClB’-Cu2-02B C 1Bt-Cu2-C 1B 01A-C9A-O2A OlA-C9A-ClOA 02A-C9A-C10A 01B-C9B-O2B 0 1 B-C9BClOB 02B-C9B-C1 OB

138.0 (3) 97.7 (2) 123.7 (3)

127.5 (3) 101.0 (2) 125.5 (3) 90.5 (3) 102.3 (3) 103.2 (3)

85.5 (3) 81.4 (3) 105.9 (3) 125.7 (6) 117.2 (6) 117.0 (6) 125.0 (7) 117.7 (6) 117.4 (6)

126.3 (6) 117.8 (6) 115.9 (6) 126.1 (7) 118.0 (6) 116.0 (6)

‘Atoms marked with a prime indicate a symmetry transformation by f , j j , i. because of the lability of the Cu-CO bond,’ a structure was proposed for the species in solution: Ph

Ph

C5B

6A

+

2co

C4B

C4A

-

68

s

C3A

Ph’

P‘

C7A

c3B

C7B

h

2

N1B 1B

Ph

1 S = MeOH, Ph-

< 0

= Ph-\

No

The structure proposed for 2 had crystallographic support from the case of the diphenylacetylene derivative [ C U , ( ~ - P ~ C O ~ ) ~ (PhZC2),] (3).6 A closer similarity can be found, however, in the compounds formed from the reaction of 1 with p-tolyl isocyanide. Reaction 2 gave different results, however, depending on the R

I

c14

R

I

[ i j

solvent used. Reaction of 1 with p-MeC6H4NC in EtOH gave a crystalline solid having a structure similar to that of 3. A single C-N band in solution (EtOH) and in the solid state was observed

C138

Figure 1.

ORTEP

drawing of complex 4 (40% probability ellipsoids).

for the isocyanide at rather high wavenumber (2152 cm-’), as expected for an electrophilic metal like Cu(1). The solid-state analysis showed, however, that the dimeric units (Figure 1) have significant interactions with one another to form a sort of tetrameric complex, reported in Figure 2. Each copper(1) in the dimeric unit (Figure 1) has a nearly planar trigonal structure, with Cul and Cu2 out from their coordination planes ClA, OlA, 0 1 8 and ClB, 0 2 A , 0 2 B (Table SVII) by 0.116 (3) and 0.084 (2) %.,respectively. The dihedral angle between these two co~)~] ordination planes is 24.6 (2)O. The [ C U ~ ( P ~ C Ofragment maintains the same structural characteristics as in the original

240 Inorganic Chemistry, Vol. 26, No. 2, 1987

Toth et al.

C1A

Figure 2. Projection of complex 4 showing the interactions between two dimers related by a center of symmetry. Phenyl rings are missing for clarity.

CBC

c138

tetrameric complex2 and in 3,6 such as the Cw-Cu proximity of 2.750 (2) A. The Cu-0 bond distances (Table V) are very close to those reported for 36 [mean value 1.957 (10) vs. 1.953 (9) A] and significantly shorter than those in l2[mean value 1.839 (6) A]. The significant lengthening of Cu2-02B [2.031 (6) A] must be related to the different coordination number of Cu2, since this copper interacts at rather close distance [Cu2--ClB’ = 2.757 (7) A] with the isocyanide carbon of an adjacent dimer (Figure 2). In addition, a small deviation from the linearity at the Cu-CNR unit was observed [Cu2-ClB-NlB = 175.6 (6); C l B - N l B 4 2 B = 173.4 ( 6 ) O I . Bond distances for the Cu-CNR fragment (Table V) are very close to those reported for the few copper(1)-isocyanide complexes structurally studied so far.I7 The incipient semibridging bonding mode of the isocyanide ligand seems likely. Such an interaction brings in a close proximity Cu2-.Cu2’ [2.860 (2) A]. This sort of close interaction between dimers to form a tetrameric unit vanished when reaction 2 was carried out in THF, since a further isocyanide molecule bonds to one of the copper(1) ions: R

I

R

C16

Figure 3.

ORTEP

C13A

drawing of complex 5 (40% probability ellipsoids).

fragment are observed for the isocyanide bonded to Cul [CulC1C-N1C = 170.8 (8)O; Cul-CIA-N1A = 172.3 (7)OI. The two aromatic rings C2A...C7A and C2B...C7B are almost parallel. Structural parameters for the Cu-CNRI7 units and PhC022s6,7 ligand are in the usual range. Reaction of [CU(P~CO~)]~ with Azo Compounds. A study on the reactivity of azo compounds with 1 is suggested by the close resemblance of the azo group to the C W bond,ls because both are unsaturated substrates that can undergo hydrogenation. Copper(1) carbonylato species are, in fact, the first well-defined homogeneous catalysts for hydrogenation.s While the reaction of 1 with azobenzene led to some labile species, which we were not able to identify analytically or spectroscopically, more successful results were obtained from the reaction of 1 with ring-fixed azo compounds, like benzo[c]cinnoline or phthalazine. Reacting a T H F solution of benzo[c]cinnoline with 1, we isolated a complex having the polymeric structure

I

CCu(PhC02)34

+

2

1

6 R = p-MeCeH4

The solvent is the factor that causes the reaction between 1 and p-MeC6H4 to produce 5 instead of 4. Complex 5 has two CEN stretching frequencies at 2125 and 2145 cm-’. An ORTEP view of 5, which crystallizes with a molecule of THF, is shown in Figure 3. The Cu-C and Cu-0 bond distances of the three-coordinate copper closely resembles those found in complex 4, while those of the tetracoordinate copper(1) are significantly longer (Table V). The two isocyanides bonded to Cul are significantly different [Cul-ClA = 1.857 (7) 8,vs. Cul-ClC = 1.926 (8) A].17 It also must be mentioned that a sort of semibridging interaction involves Cu2 and the C1A carbon of an adjacent isocyanide [Cu2A-C1A = 2.762 (8) A]. Furthermore, Cu2 is significantly displaced [0.269 (2) A] from the plane defined by ClB, 02A, 0 2 B toward C1A. The Cul-Cu2 distance is significantly longer than in 4 [3.020 (3) A]. Weak van der Waals interactions exist between dimers. Small but significant deviations from the linearity of the Cu-CNR (17) Toth, A.; Floriani, C.; Pasquali, M.; Chicsi-Villa, A.; Gaetani-Manfredotti, C.; Gaustini, C. Inorg. Chem. 1985, 24, 648-653. Pasquali, M.; Floriani, C.; Gaetani-Manfredotti, A,; Chiesi-Villa, A. Ibid. 1979, 18, 3535-3542.

PhNb

P bP & h’h ‘

6

An ORTEP view of the structure is reported in Figure 4. The polymer is built up by the centrosymmetric dimers [Cu(PhC02)], bridged by the azo group from benzo[c]cinnoline. Steric hinderance is probably responsible for the stoichiometry of 6, so that copper(1) can bind a single nitrogen atom and is three-coordinate (vide infra). The Cu.-Cu distances along the chain are 2.788 (2) A within the dimers and 3.262 (2) A across the dimers. The conformation of the eight-membered ring [ C U ~ ( P ~ C Ois~ ) ~ ] completely different from that observed in 3-5, where the ring is folded along the Cw.Cu direction by a value close to 90°; the ring is nearly planar in 6. Copper(1) can be considered either three- or four-coordinate via weak interaction with an oxygen atom (18) Carty, A. J. Organomet. Chem. Reu., Sect. A 1972, 7, 191-243. Ack-

ermann, M. N.; Kou,L. J. Inorg. Chem. 1976, 15, 1423-1427.

Dinuclear Copper(1) Benzoato Complexes Table VI. Bond Distances cu-0 1 CU-N cu-02‘ cu-CU’ cu-02”’ N-N“ N-C8 C8-C9 C9-C9” C9-C 10

(A) and Angles (deg) for Complex 6“ 0 1-Cu-N

1.897 (4) 2.332 (4) 1.928 (4) 2.788 (2) 2.741 (4) 1.306 (8) 1.376 (6) 1.415 (7) 1.406 (11) 1.406 (8)

N”-N-C8 N-C8-C 13 N-C8-C9 C8-C9-C9” C8-C9-C 10 ClO-C9-C9”

Inorganic Chemistry, Vol. 26, No. 2, 1987 241

120.1 (4) 116.5 (4) 122.9 (4) 116.8 (4) 118.2 (5) 125.0 (5)

101.6 (2) 160.8 (2) 97.5 (2) 78.3 (1) 155.2 (1)

01-Cu-02’ N-CU-02’ CU’-cu-0 1 CU’-CU-N ClO-Cll Cll-c12 C12-C13 C 13-C8

1.371 (10) 1.401 (9) 1.380 (8) 1.404 (8)

c9-c1o-c11 ClO-Cll-C12 Cll-Cl2-Cl3 C12-C13-C8 C13-C8-C9

‘Symmetry transformations: single prime, -x, -y,

01-C7 02-C7 C7-C1 Cl-C2 C2-C3

120.4 (5) 121.4 (6) 119.5 (6) 119.9 (5) 120.6 (4)

-2; double

Cu’-Cu-O2’ CU’-cu-0”” 02’”-cu-0 1 02”’-Cu-O2’ 02”’-Cu-N 1.255 (6) 1.241 (6) 1.501 (6) 1.391 (7) 1.375 (9)

0147-02 01-C7-C1 02-C7-C1 C7-Cl-C2 C7-Cl-C6

prime, -x, y ,

124.6 (5) 116.5 (4) 118.9 (4) 120.0 (4) 121.0 (4)

- 2; triple prime, x , -y,

83.9 (1) 128.1 (1) 100.4 (2) 85.2 (2) 76.6 (2)

c3-c4 c4-c5 C5-C6 C6-C1

.

C2-Cl-C6 Cl-C2-C3 C2-C3-C4 C3-C4-C5 C4-C5-C6 C5-C6-C1

1.373 (9) 1.369 (10) 1.401 (9) 1.381 (7) 119.0 (5) 120.8 (5) 119.8 (6) 120.6 (6) 119.9 (6) 119.9 (5)

+ z.

of an adjacent molecule [Cu.-O2’’’ = 2.741 (4) A], Cu being 0.018 A out of the coordination plane ( 0 1 , 02’, N ) toward 02”’. The Cu-0 bond distances are significantly shorter (Table VI) than those in complexes 3-5. The very short N-N bond distance [N-N” = 1.306 (8) A], which has to be compared with that in ([Fe(CO),]2[bzocin]]’9 [N-N = 1.399 (8) A], agrees with the interaction occurring through the nitrogen lone pairs rather than through the N=N multiple bond. The bridging rather than the chelating bonding mode is expected because of the geometrical orientation of the lone pairs. On the other hand, the rather long Cu-N bond distance [2.332 (4) A] is related to the low basicity of the heterocyclic nitrogens and has to be compared with those significantly shorter involving amino groups.” Less sterically demanding azo derivatives, like phthalazines, reacted with 1 in a 1:l Cu:phthalazine molar ratio: tCu(PhCQ)14

+

4

1

*,,.-

XI

-

Y,

112

Figure 4. ORTEP drawing of the polymeric structure of complex 6 (40% probability ellipsoids).

?

We do not have any structural evidence for 7, for which we did not get any suitale crystals for X-ray analysis. The structure we propose, however, has significant support from the structure of 6. The steric hindrance that determines the difference between the structures of 6 and 7 seems to be more associated that the azo compound than the copper(1) moiety. As a matter of fact, in reacting benzo[c]cinnoline with copper iodide, we obtained a (19) Doedens. R. J. Inorr. Chem. 1970. 9.429-436. (20j R = I ~ ~ A F ~ / ~ I F . , ~ ;=O R ~ (21) Defined as [Ew(lF0l.- IFJ)/ ( N o- N J ] , where No is the number of observations and N , IS the number of refined parameters.

q~q~jz~q~,,i.

compound with a 2: 1 Cu:benzo[c]cinnoline molar ratio, [Cu212(bzocin)], (8), for which we can propose the same structure we found for 6,except that the dicopper unit is Cu212. The reaction of CUI with phthalazine gave a compound with a 1:l Cu/ phthalazine molar ratio, [Cu(I)(phz)], ( 9 ) , for which we can likely assume a structure similar to that of 7. Solution studies of the compounds reported in this paper are largely prevented by their insolubility in the most common innocent solvents. On the other hand, the use of highly coordinating solvents, which can achieve the solubilization of the complexes reported, may affect too much the nature of these compounds, which are normally labile with weak but significant interactions in the solid state. Acknowledgment. We thank the C N R and MPI (Rome). Registry No. 1, 62914-01-6; 4, 105900-32-1; 5, 105900-31-0; 6, 105900-33-2; 7, 105900-29-6; 8, 105900-34-3; 9, 105930-62-9; azobenzene, 103-33-3. Supplementary Material Available: Listings of hydrogen coordinates (Tables SI-SIII), thermal parameters (Tables SIV-SVI), and leastsquares planes (Table SVII) for compounds 4-6 (7 pages); listings of observed and calculated structure factors for the three compounds (33 pages). Ordering information is given on any current masthead page.